In the related art, a storage device for archives which manages fixed contents is used in order to collectively store, for a long period of time, digital contents whose data is not to be modified, such as music, movie, e-mail, image, and document data. The storage device has a plurality of storage media (e.g., disks and tapes), and writes various digital contents (hereinafter, referred to as data) onto the storage media. In addition, according to a reference request from a user, the storage device reads stored data and transfers the data to a terminal of the user.
In such a storage device, when writing data onto a tape, data is written in order of data whose written date is early. For example, as shown in FIG. 9, a written date of data 1 is “08/03/15”; a written date of data 2 is “08/04/21”; a written date of data 3 is “08/05/20”; a written date of data 4 is “08/06/11”; and a written date of data 5 is “08/09/30”.
In such a case, as shown in FIG. 9, the storage device writes data onto a tape in order of data whose written date is early, and thus data is stored on the tape in order of the data 1, the data 2, the data 3, the data 4, and the data 5.
In addition, in the storage device, when data whose storage period has elapsed is present on the tape, management information on the data whose storage period has elapsed is deleted, so that the user cannot refer to the data on the tape. Moreover, in the storage device, when deleting data itself on the tape, the data is overwritten multiple times in accordance with NCSC method (NCSC-TG-025) or United States Department of Defense method (DoD5220.22-M).